The ICO said the records had been sold through brokers to rival mobile firms, so those firms could cold-call T-Mobile customers when their contracts were due to expire, in order to offer them alternative contracts. The records were sold for substantial amounts of money, according to an ICO press statement on Tuesday.

An accompanying ICO press statement did not specify which mobile operator had been involved. However, it emerged through reports on Tuesday that T-Mobile had kicked off the ICO investigation when it approached the watchdog with concerns about its employees.

T-Mobile said in a statement on Wednesday that other parts of the mobile-phone industry had been involved in the misappropriation of customer data.

"While it is deeply regrettable that customer information has been misappropriated in this way, we have proactively supported the ICO to help stamp out what is a problem for the whole industry," said T-Mobile.

An ICO spokesperson on Wednesday declined to say which phone companies had allegedly bought the T-Mobile customer data, and declined to say if or when the case would go to court.

"It's too early in the investigation to say," said the spokesperson. The ICO is currently preparing a prosecution file.

Tom is a technology reporter for ZDNet.com, writing about all manner of security and open-source issues.Tom had various jobs after leaving university, including working for a company that hired out computers as props for films and television, and a role turning the entire back catalogue of a publisher into e-books.Tom eventually found tha...
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